Charging battery whilst away.

Hello knowledgeable folk. I have to go into hospital for a big op before too long and the car will be laid up in our garage. Knowing that batteries in our cars are notorious for going flat exceedingly quickly, I am planning to connect my CTEK via an extension lead and carefully closing the boot and leaving it. I know CTEK say this is ok, but is it? Would it still charge if I left the boot open?The reason I say this is because the garage will be used whilst I am away, and it is possible that young grandson or someone else may unwittingly trip over the lead or turn the power off and I am paranoid about coming home to a flat battery and no access to the battery in the boot. If that did occur, can the car be started by the RAC by connecting power under the bonnet to the suitable terminals?
Any advice to this ignoramus would be gratefully received.
Many thanks, Angus.